What GPU will work for the new ARM CPUs?

[askunk]

So far we've seen spectacular performances by the GPUs on iPads and iPhones. Those few graphic cores integrated on Apple APUs work great and reach easily 120 fps in games with Metal on pretty decent resolutions (the iPad), albeit dealing with a "stripped down" version of a PC game.

However, what does it take to sport an Apple GPU for a desktop computer such as the iMac, once Apple makes the switch?

 

[Moonjumper]

I expect Apple to follow the same format as on iPads and iPhones, but freed of the thermal and power contraints of those devices. So higher clock speeds and more cores, with many more cores on the higher performance devices.

 

[Falhófnir]

Integrated graphics are really starting to eat into lower end dedicated territory even on Intel (traditionally weak in this area). Tiger lake is meant to be another significant step up, even on top of the one Ice Lake brought. Apple's integrated graphics solutions on the iPad AX chips in particular are really quite potent, with the extra thermal headroom of a laptop form factor, I don't think it's inconceivable the need for dedicated graphics is removed even for entry level iMacs and 16" MacBook Pros. The higher end machines will likely keep using whatever AMD bring out for a good while yet, maybe until Apple begin developing their own graphics chips as well?

 

[sublunar]

I draw your attention to the deal that was recently reached with Imagination Technologies - a new multiyear contract no less.

Sustained performance in an actively cooled environment should be a real test for Apple's ARM CPUs going forward.

 

[Falhófnir]

I draw your attention to the deal that was recently reached with Imagination Technologies - a new multiyear contract no less.

Sustained performance in an actively cooled environment should be a real test for Apple's ARM CPUs going forward.

Well remembered, are they up to making Nvidia/AMD competitive graphics chips (either integrated or discrete) though?

 

[sublunar]

Well remembered, are they up to making Nvidia/AMD competitive graphics chips (either integrated or discrete) though?

Barefeats test suggests the A12Z is on par with the 'top' 2020 MacBook Pro 13" Iris Plus Graphics G7 on Metal benchmarks - and beats it on multicore Geekbench. This is pretty impressive considering the 12.9" iPad Pro (probably single digits wattage TDP) is going up against a 28w TDP CPU while driving a panel (2732 x 2048) that is higher resolution than the 13" Macbook Pro at (2560 x 1600).

And this is up against a current generation Ice Lake CPU as used in the 2020 MacBook Pro which was a significant update on the 2019 version.

Notebookcheck.net seems to rate the Ice Lake G7 graphics quite highly - above all previous Iris Plus and Pro graphics (including the Iris Pro 580 that Apple never used).

That site also seems to suggest it's less powerful than the Radeon Pro 450 dGPU that was used in the MacBook Pro 15" base model in 2016 which is understandable but quite good going for integrated graphics on a 28w CPU vs a dgpu that fit into a sub 35w TDP budget by itself 4 years ago.

The proof will be in how Apple manage to run gaming sessions for hours at a time - something which may require an AppleTV redesign to incorporate a dynamic or larger heatsink with better passive airflow. In this regard, staying quiet and using single digit watts may be a feature for the AppleTV.

Obviously, we may be less than a year away from an A14x which will move things on even more but it's becoming clear that ARM CPUs could take over pound for pound for Intel U CPUs with the integrated GPU as it stands.

How they marry up with a discrete GPU - if at all - remains to be seen but imagination technologies may be looking into a scaled increase in integrated graphics rather than Apple moving to bring in Nvidia or AMD for their ARM laptops.

 

[jerwin]

The problem is that a 4 core intel chip and Iris (pro) graphics is no longer even close to the state of the art. Nvidia's RTX and AMD's Ryzen are where it's at.

 

[playtech1]

It will have to be an Apple GPU as to do otherwise defeats some of the point of going ARM - namely total control by Apple over the key hardware components.

I am doubtful that the Apple GPUs will be much ahead, if at all, of what is current on the market when the ARM Macs arrive, since AMD will have integrated Navi on its APUs at that point and Intel has invested in its Xe architecture, but equally Apple has the track record on iOS to make sure it's first laptop effort will be competitive at least.

I think some of the success of Apple's performance has come from its use of TSMC's 7nm process rather than design brilliance (although those more in the know may correct me).

 

[sublunar]

The problem is that a 4 core intel chip and Iris (pro) graphics is no longer even close to the state of the art. Nvidia's RTX and AMD's Ryzen are where it's at.

Yes but what's the performance like at sub 10w? It may be better to compare to the 4000U series AMD CPUs, and we don't know what Imagination Tech's GPU will be like given active cooling.

 

[jerwin]

Yes but what's the performance like at sub 10w?

Considering the forum we're in, does power consumption really matter? No, the imacs are best known for their super high resolution screens that will tax the life out of any subpar GPU. It would be better for Apple to redesign the case for better thermals, then it would be for Apple to admit defeat and go with a mobile GPU.

 

[askunk]

Sure, I wasn't much worried about the APUs. The issue are the HPC, the GPGPU and the 3D performances I would expect from an ARM desktop Mac.

 

[sublunar]

Considering the forum we're in, does power consumption really matter? No, the imacs are best known for their super high resolution screens that will tax the life out of any subpar GPU. It would be better for Apple to redesign the case for better thermals, then it would be for Apple to admit defeat and go with a mobile GPU.
View attachment 914084

I don't know if you've noticed but Apple use 'mobile' Pro SKU GPUs for their iMacs to hit a thermal target and have done so for years. Even integrated Intel GPUs will display a 4k desktop and one Apple SKU used Iris Pro 6200 to run a 4k panel. And power consumption does matter because less power consumed = smaller, thinner, less noisy enclosure. There - I said the Jony Ive word that must not be spoken

Nobody's gaming on an iMac so that doesn't really matter, with GPU mainly being used to render video better in real terms.

Having said that, RDNA2 is coming at the end of the year and apparently has a better performance per watt than RDNA by 50%. RDNA is the architecture driving the AMD Pro 5300 and 5500 in the MacBook Pro 16" and in the PC desktop 5500, 5600, and 5700XT GPUs.

RDNA2 - 'Big Navi' is being used in PS5 and Xbox Series X and is a quantum leap in performance per watt, seemingly able to match the Nvidia 1080 in horsepower while sipping 'mobile' watts. Those consoles won't be space heaters so there must be something in these rumours.

In the PC range you'd expect those to start with a 6 - ie 6300 Pro, 6500 Pro, 6600, 6700, etc.

If true this is exactly what Apple would want to put into an iMac that has mini LED and Comet Lake/Rocket Lake CPUs next year. What a super-cycle upgrade a 2021 iMac must be. I'm not talking to the folks on this thread who must be salivating at the thought of being able to play games - video editing at a decent pace on a civilised machine would be fine for me.

If the RDNA2 information is true then Nvidia have indeed been resting on their laurels and, like Intel, may have to scramble to catch up as AMD hit another home run.

Let's swing back to ARM though. The topic in discussion here is iMac - and a late 2021 iMac could end up being ARM powered and the thickness of an iPad. While Apple hasn't proven to be able to scale ARM up to desktop class TDPs (yet) I imagine that a super light desktop would be interesting to some (fully expecting the performance wizards to jump on this).

 

[jerwin]

Nobody's gaming on an iMac so that doesn't really matter, with GPU mainly being used to render video better in real terms.

The real bonus--arm has no boootcamp support, which will finally disabuse people of the whole notion.

 

[jerwin]

That's targetting a 10 TFlop machine.
Still thinking about fan noise?